A vehicles battery is the energy source ,that the vehicle uses in order to operate and store energy. Car batteries use a 12 volt system which consists of 6 cells in the battery. Each cell in the battery is designed to produce around 2.1 volts at full charge. These batteries are used for lighting, electronics in the car, and ignition of the vehicles engine. Larger vehicles such as a semi trucks may use a 24 volt battery system, or a parallel string of smaller batteries. Automotive batteries are usually rechargeable and are kept in the engine compartment. These batteries work best when they are kept in a dry and cool environment which helps prevent corrosion of the plates, and high rates of self discharge. In average conditions, a car battery will last between 3 and 5 years before it needs to be replaced. Batteries are rated on their cold cranking amperes. This looks at the amount of current a battery can put out at 0 °F. The test looks at the current a battery can put out for 30 seconds and at 1.2 volts per cell. It is done at lower temperatures because it is more demanding on the battery.
Vehicle batteries are used to power the starter, which in turn will rotate the flywheel and turn the crankshaft which starts the engine. After the engine is started, an alternator which converts power from a belt and pulley system connected to the engine will recharge the battery when the engine is running. Vehicles normally use a shallow cycle battery to start up the car. This battery excels in delivering large bursts of power for a short period of time, making them perfect for the startup of an engine. Deep cycle batteries which are used in recreational vehicles are designed to provide continuous amounts of power for long periods of time.
The most common type of battery used in vehicles is the lead-acid battery. This battery is made up of lead plates and lead dioxide plates. These are submerged in an electrolyte solution that is 65% water and 35% sulfuric acid. This will cause a chemical reaction which will release electrons that flow through conductors and create electricity. When a lead-acid battery discharges, the acid of the electrolyte reacts with the plates, which changes their surface to lead sulfate. When this battery is recharged, the lead sulfate reforms into lead oxide and lead. This restores the plates to the original condition making them ready to repeat the process. Sometimes these lead-acid batteries need to be refilled with distilled water when empty. This distilled water can be broken down by excessive over charging of the battery.
There is also a new more efficient and liquid free battery called the optima battery. This battery is more reliable and longer lasting than a standard acid battery. The unique spiralcell design allows for more plate surface, closer plate spacing, and the ability to use high purity lead. This all leads to low resistance inside the battery which allows the battery to be significantly smaller than a standard battery which produces the same amount of voltage. The purity of the lead in this battery also helps to keep self discharge rates low compared to the alloys in conventional batteries which are more prone to letting electrons transfer. Optima batteries are also lighter than traditional batteries, which is why they are often seen in high performance vehicles. In an optima battery, the lead plates and separator are bound tightly together which makes the battery resistant to leaks. This also makes the battery extremely resistant to vibrations that a vehicle might encounter.